The present invention relates generally to a vehicle anti-theft device, not necessarily restricted to vehicles since it can be applied to any hydraulic or pneumatic brake system of automobiles, trucks, heavy equipment, aircraft or machines, and more particularly to an improved device of the type that advantageously uses the system's braking fluid to prevent movement, unless by an authorized user.
Anti-theft devices that take advantage of the brake fluid principle and the rotary valve port disorientation principal are already well known and exemplified by U.S. Pat. Nos. 1,433,709, 1,527,670, 3,468,586, 3,515,442, 3,617,100, 3,653,730, 3,800,279 and 4,018,314.
U.S. Pat. Nos. 3,653,730 and 4,018,314 give adequate summary of the reasoning for the need for such a device.
Of all the patents listed in the foregoing, only U.S. Pat. Nos. 1,433,709 and 1,527,670, although for gasoline systems which would require the device to be mounted outside the passenger compartment due to explosive atmosphere and U.S. Pat. No. 3,468,586, are devised on the principle or rotary valve port disorientation. To anyone familiar with the art, it can easily be seen that similarity of design and construction is totally lacking between the patents noted and this new innovation of construction.